Recommended Torque Values
For precision connectors, as defined by the IEEE P287 standards committee, we use their values. For our products P287 covers 1.0mm, 1.85mm, 2.4mm, 2.92mm, 3.5mm, 7/16, 4.3/10, Precision N’s (18Ghz) & TNC’s (18Ghz). Values have decreased over time, especially 3.5mm’s going from 13 in-lbs to 8.
SMA Torque Wrenches are not covered by P287 as they’re not considered precision connectors. We recommend 4 in-lbs for brass SMA Torque Wrenches; 5 in-lbs sma torque wrenches for lab tests; & 8 in-lbs sma torque wrenches for final installation. Mil-specs specify 8-10 in-lbs and stainless steel sma’s. Our industry has come up with brass sma’s to reduce cost; & while there’s no standard, manufacturers recommendations vary between 3-5 in-lbs, so we recommend 4 in-lb sma torque wrenches.
Also re SMA’s: Keysight engineers have told us they have seen “oil canning” effects on some manufacturers sma’s when torqued between 8-10 in-lbs; and 5 in-lbs is sufficient for all electrical tests. Hence the Keysight SMA Torque Wrenches are set to 5 in-lbs. For lab use we go with their recommendation, but still follow mil-spec recommendations of 8 in-lb sma torque wrenches for final installation, for both environmental concerns & a more permanent connection. Hence depending upon connector construction & stage of testing, either 4, 5, or 8 in-lbs is called out for SMA's.
7/16’s per P287 have 2 values; 20 in-lbs for electrical test, 221-300 in-lbs for installation. These are in the new p287 draft, we don’t expect any changes.
Standard Brass N’s & TNC’s work fine finger tight; but some people like to use torque wrenches for uniformity; we surveyed various manufacturer’s recommended torque values to come up with our torque wrench settings. Precision N's & TNC's, those made of stainless steel & good to 18ghz, should be used with torque wrenches.
Here are our recommendations:
|1mm||S Steel||4-6 in-lbs||SMC||Brass||2-3 in-lbs|
|2.4mm||S Steel||8 in-lbs||SSMA||S Steel||8 in-lbs|
|2.92mm||S Steel||8 in-lbs||SSMA||Brass||4 in-lbs|
|3.5mm||S Steel||8 in-lbs||SSMC||Brass||2 in-lbs|
|4.1/9.5||Brass||89 in-lbs||TNC||S Steel||12 in-lbs|
|4.3/10||Brass||44 in-lbs||TNC||Brass||5 in-lbs|
|7/16||Brass||20 in-lbs test, 221-230 in-lbs assy||Type N||S Steel||12 in-lbs|
|SMA||S Steel||5 in lbs test, 8 in-lbs assy||Type N||Brass||8 in-lbs|